Articles composed of cellulose esters.



UNITED STATES P tZFENT OFFICE.

HARRY S. MORK, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO CHEMICAL PRODUCTSCOMP ANY, 0F BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

ARTICLES COMPOSED OF GELLULOSE ESTERS.

No Drawing. Original application filed February 10, 1910, Serial No.543,098.

filed May 19, 1910.

To all whom it may concern:

Be it known that I, HARRY S. Monk, a citizen of the United States,residing at Boston, in the county of Suffolk and State of Massachusetts,have invented an Improvement in Articles Composed of Cellulose Esters,of which the following is a specification.

In Letters Patent No. 1,061,771, dated May 13, 1913, a process oftreating cellulose esters, such as cellulose acetate, is em bodied,consisting essentially in producing a lower cellulose ester of a fattyacid by removing from a higher ester a portion of the combined acid.

In carrying out the process therein set forth the higher ester of thefatty acid is treated with a saponifying agent until a portion of thecombined acid is removed.

This invention relates to sheets, or films, filaments and the like,composed in part of the lower esters of the fatty acids, as the loweracetates, which also involves the exercise of the invention set forth inmy aforesaid patent of which this application is a division, yetcomprehends new and useful features.

This invention comprises sheets or films and filaments and the like,made of triacetate of cellulose, such as may be prepared according to myPatent #85 1374, and such portion thereof as is desired changed by theremoval of a part of the combined acid, as hereinafter set forth. Such asheet or film, filament and the like, is adapted for many uses where thequalities of the triacetate are desirable in some part of the sheet orfilm, filament and the like, and the qualities of a lower acetate aredesirable in other portions thereof. For instance the back of aphotographic film base may be composed of the triacetate and the surfacecomposed of a lower acetate; or a pattern on the surface of the base maybe composed of a lower acetate; or threads may have an interior of thetriacetate and an exterior of a lower acetate; or a part of a film maybe changed to the lower acetate from front to back, leaving theremainder unchanged. In short many combinations of this nature may beproduced readily involving my invention.

In the process of my application aforesaid partial saponification orremoval of a Specification of Letters Patent.

Patented Sept. 23, 1913.

Divided and this application Serial No. 562,318.

part of the combined acid of the ester is effected in a number ofdifferent ways and by the application of usual or suitable saponifyingagents, such as sodium or potassium hydroxid, hydrochloric or sulfuricacid, or by some reagents not ordinarily used for the purpose, such assodium carbonate and ammonia. For example, if cellulose triacetateprepared according to my Patent #854,374, be allowed to stand in aqueousammonia of specific gravity 0.9 for fifteen or sixteen hours, at atemperature of say 15 to 20 (3., saponification will gradually takeplace, although conversion toward the di-acetate and the monoacetatewill not take place in definite stages. These results may likewise bereached by using a stronger solution for a shorter time or thesaponification may be carried further if desired by stronger chemicals,greater heat, or longer time or both.

In the present invention the sheets or films, filaments and the like,are treated superficially whereby a portion only of the sheet or film,filament and the like, is changed. Superficial saponification is readily effected by subjecting the portion it is desired to change. from thetriacetate to a strong hot caustic soda solution or other activesaponifying agent for a very short time, as for instance, a 10% sodiumhydroxid solution for one or two minutes at 60 or 70 C. Thesaponification will proceed further the longer the reaction is permittedto continue. Or a thin layer of a viscous menstruum, like a starch orgelatin solution containing the active saponifying reagent, may beapplied to the surface of the film.

In case it is desired to effect saponification locally in spots orconfigurations on the surface, the thick solution can be printed uponthe film in any desired pattern. For many purposes it is not harmful ifthe reaction continues-so long that the film is superficially saponifieduntil the acid groups have been completely removed.

One example where the exercise of my invention is useful is in thetreatment of cellulose acetate films for photographic purposes. I havediscovered that when such films are partially or superficiallysaponified they are, by reason of this modification, put

in condition so that the gelatin emulsion or substratum will morereadily adhere to them, owing to the increased water absorptive capacityof that portion which has been partially or completely saponified, andthe properties of the film may be varied greatly according to the extentof the saponification. Another application is in the case of artificialsilk. The number of dyes that can be dyed directly from aqueoussolutions on artificial silk made from cellulose triacetate is verylimited. When the artificial silk has been subjected to the action of asaponifying agent, in accordance with this invention, I find that. byreason of this treatment the number of dyes available for dyeing thematerial is very materially increased. Another advantage of the exerciseof my invention is the fact that even if the original cellulosetriacetate is very flexible and strong, the

flexibility and strength are noticeably increased by subjecting thetriacetate to partial saponification. Furthermore, a sheet or film or afilament superficially saponified by my process is quite distinct fromany sheet or film or filament which could be ,made by attempting tocombinetwo sheets, one made of the triacetate and one of the tion of thecombined acid.

2. As a new article of manufacture, a sheet,,film or filament composedof an 'in-. separable combination of cellulose of pro.- gresslvelyvarying degrees of acetylation-including the triacetate and a loweracetate prepared by removing superficially or 10-' cally from thetriacetate a portion of the combined acid.

3. As a new' article of manfufacture, a sheet, film or filament ofcellulose'triacetate having its surface saponified to produce "anarticle of. progressively varying degrees of acetyla-tion.

4:. Asa new article of manufacture, a film, filament, sheet or structurecomposed of cellulose of progressively varying def grees of acetylationand which 1s physically homogeneous but chemically heterogeneous in itsrelations to water, dyes and solvents.

5. As a new article of manufacture, a

sheet, film or filament composed of cellulose acetate, superficiallysaponified.

6. As a new article of manufacture, a

sheet, film or filament composed mainly of an acetate ofcellulose higherthan the diacetate and having a surface composed of an v acetate ofcellulose lower than the triacetate.

7 As a new article of manufacture, a base for a photographic filmcomposed of a cellulose ester, superficially saponified.---

8. As a new article of manufacture,- a-base for a photographic filmcomposed of a-cellulose ester, the surface of which is composed of alower ester than the remainder.

9. As a new article of manufacture, a base for a photogra hic filmcomposed of a cellulose ester, a portion of the surface of which iscomposed of a lower ester than the remainder.

.10. As a new article of manufacture, a base fora photographic filmcomposed of triacetate of cellulose with a surface composed of a loweracetate of cellulose.

IL-As a new article of manufacture, a

photographicfilm-base having a surface of an acetate of celluloselower-'than-the-triacetate and a base of a-liigher degreeof acetylatio'nthan the surface.

base for a photographic'film cc i tin f a support comfposedof=triacetate of cellulose and: a sur 13. As a new photographicfilm-base comp f e of the triacetate of cellulose: superficiallysaponified;

In testimony whereof I have-signed my two subscribing-witnesses. Y

Witnesses: B. J. Norms,

Y H. B. 1'D'Av1s.-

ace composed of a lower acefate of cellulose inseparably combined with'thesupport.

- 12. As a new 'article of manufacture, a

article of -ma-nufacture', a

name to this specification in the presence of

